Around the window frames I add another layer of white and then aim good with the black, so that as less as possible gets on the white. The dimming colour itself doesn't harm much.
I know it would be more effective to start with the black, but I am much too lazy for all the masking work and don't mind the extra gram of colour. By the way I use the Tamiya lexan colour white. I find it less "transparent" for darker following colours.